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Comment by ec109685 | Hacker News Reader

Why didn't the Apollo 10 astronauts fly back up as part of Apollo 11 since they handled their mission so well and the 11 was pretty much identical?

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Maybe because it was considered too stressful to do two missions close like that?

Maybe because that's how the military do things - recce and offensive action are usually done by different units or subunits within a unit, with the recce briefing the other group.

Also, the effects of space travel were barely known then. Even today we have little idea what actually happens to the human body when it's in space; only a few weeks ago, NASA published the results of the first twin study on space travel and had a lot of new and interesting findings. In the 1960's we knew even less, and given an abundance of caution, it's probably safest not to recover a crew of astronauts from the Moon and then immediately send them back to the Moon.

Right - the recce proved a fresh team could reach the moon. So that's what they did - sent a fresh team to the moon. Sending a team back to the moon would have been something untested.

Apollo 8 went to the moon and the crew didn't turn into xenomorphs. I don't think they were quite unsure what to expect out there but there were lots of other factors in the scheduling.

> Apollo 8 went to the moon and the crew didn't turn into xenomorphs.

I obviously wasn't suggesting anything as stupid as that, was I?

What I mean is I don't believe either of 'they had no idea what space would do to them' or 'they were just following some military convention' had much to do with the way they scheduled crews.

This is sort of what I was getting at with the phrase “abundance of caution”. At this time we were still quarantining people who returned from the moon.

One thing we do know (and knew at the time) is that the earth->space and space->earth transitions require a period of adjustment. The added stress of repeating this adjustment has, so far as I know, still not been tested, let alone understood.

Yes of course. But as a factor it would be far lower in importance than lots of other much more basic ones. Like, say, the fact that the missions were quite different, you have to prepare crews for them, you have to prepare backups, you have a limited set of highly trained, highly ambitious overachiever volunteers to pick from, all of whom expect to fly (in history-making missions), etc, etc, etc.

The Apollo 11 backup crew was the prime crew for Apollo 13.

Crew scheduling was somewhat messy, but generally the backup crew for a mission were the prime crew for the next+2 mission. (13 and 14 crews were swapped for reasons).

Let’s not forget that these were all very complicated missions and not duplicative. It would be nearly impossible to train for two at once, and do it well. Too disfocussing.

This was a duplicate mission, at least according to the article.

Well, you know, except for descent, touchdown, exiting the lunar lander, performing some exploration, gathering moon rocks, re-entering the lunar lander, take-off, and lunar orbit insertion.

Yes. Identical, apart from those things.

It was an extension of the mission they just went on.

I imagine both crews were pretty well set in stone years before 10 launched.

Would make sense. If something happened to the original crew, you need to have more crews ready and already trained.

Every Apollo mission had a primary crew and a backup crew (which was usually also the primary crew of a future mission). Apollo 13 famously swapped one of their primary crew, Ken Mattingly, for backup Jack Swigert because of a risk that Mattingly had contracted rubella. Mattingly was in good health, however, which allowed him to help NASA figure out how to keep the astronauts alive after the failure of the service module.

Ironically Apollo 13 was the final spaceflight for all three of its crew but Mattingly went on to fly on Apollo 16 and a couple shuttle missions.

Then you end up like the tech company where only one guy does deployments, because he's the only guy management trusts, because he's the only guy who's ever done a deployment.

The mission details were quite different so there would have been no time for training. In addition they tried to rotate the crews and not rely on a few people.

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